Fuel pump



June-9, 1953 w. v. FALCON 2,541,196

FUEL PUMP Filed June 2, 1947 2 Sheets-Sheet l l 4 .i /00 I #2 45 v5 #24.

INVENTORI w. v. FALCON June 9, 1953 FUEL PUMP 2 Sheets$heet 2 Filed June 2, 1947 IOIau Patented June 9, 1 953 UNITED STATES PATENT OFFICE FUEL PUMP William V. Falcon, Revere, Mass.

Application June 2, 1947, Serial No. 751,831

2 Claims.

.My present invention relates to an improvement in fuel pumps and fuel injection valves for use with internal combustion engines of the type in which fuel is injected into the combustion chamber. The invention may be employed either with internal combustion engines of the compression ignition type in which the fuel is ignited by the compression alone or of the electric ignition type in which the fuel is ignited by a timed electric spark.

It is a primary object of my invention to provide a simple unitary combination fuel pump and fuel valve and a jet which premixes and diffuses warm air with the raw fuel from the valve and all of which can be installed and removed from an engine as a single unit. Further objects are to provide a non-leaking fuel pump and valve unit which operates satisfactorily for the required purposes without the necessity of parts machined to closely critical tolerances and which is therefore inexpensive to manufacture.

' My present invention provides: (1) a unit fuel pump having embodied in it a differential fuel spray valve; (2) a unit fuel pump with a spray valve which has no outlet to the atmosphere, this being made possible by an air cell on the differential side of the fuel valve; (3) a fuel valve which has a sharp cut off at the end of each injection and which, therefore, does not tend to dribble; (4) a fuel pump which may be easily primed; (5) a combined fuel pump and differential spray valve which may be easily adjusted so that the valve will open at a given pressure; and (6) a valve and mixing jet which may be used in connection with the novel cylinder head described in my companion application Serial No. 719,860, filed January 2, 1947, now Patent No. 2,493,481, in which are described arrangements by which the fuel is injected into hot air taken from the top of the combustion space so that more perfect and rapid combustion results. The combined unit embodying my invention is extremely simple and compact, has relatively few parts and can be removed and replaced by another unit quickly and easily.

The invention will be fully understood from the following description, taken in conjunction with the accompanying drawings, in which Fig. 1 is a vertical section of a portion of a cylinder block, cylinder head and a combined pump and valve unit embodying my invention. Fig. 2 is an enlarged section of the valve unit and related parts.

Fig. 3 is an end view of a jet, and r v I -Fig.- 4is a section on line 4-4 of Fig. 1.-'

A cylinder block is shown at H], a cylinder at I2, and a cylinder head at I4. Within the cylinder head is a circular dome-shaped combustion chamber [6 located over a part only of the cylinder I2. A valve body I8 is secured in a cylindrical aperture 20 in the cylinder head and makes a tight joint therewith by means of the gasket 22. A passage 24, in the cylinder head [4 leads from the top of the combustion space I6 to a vertical passage 26, which connects with an annular space 28, formed between a spray nozzle 39, screwed into a suitable aperture in the side of the combustion chamber [6, and a jet 32 which is screwed into the valve body 18. The spray nozzle has a tapered passage 34 therethrough. The jet 32 is provided with a series of longitudinal holes or passages 36, see Fig. 3, arranged to communicate at one end with the annular space 28 and at the other end with an annular space 38 between the jet 32 and a valve seat 40 which acts as a spray cone located in the valve body l8 and held in place by the jet 32 which engages a shoulder 42 on the valve seat 40 and forces it against a gasket 44. Within the valve seat 40 is a taper ing sliding valve member 46 formed integral with a piston 48 having a series of grooves 50 in its peripheral surface to maintain tight contact with a cylindrical bore 52 in the valve body. This cylindrical bore 52 is closed at its rear end by a cap 54 and gasket 56 and contains a spring 58 bearing against the end of the valve 46 and tending to hold it on its seat except when the raw fuel pressure on an annular shoulder of the valve 46 overcomes the resistance of the spring 58. The valve member 46 is also provided with a central bore 62 which communicates by two transverse passages 64 with the cylindrical bore 52 in the valve body l8. At 66 is shown a plug screwed into an enlarged threaded portion 62a of the bore 62 in the valve member 46 and providing a passage 61 and seat 66a for an auxiliary pressure relief valve 68 having a stem 10 in the passage 6! and on which is screwed a cap 12. The stem 10 may be grooved or else the passage 61 may be larger in diameter than the stem 10 as shown in Fig. 2 to allow fuel oil to pass through the passage 61 around the stem 70 when the auxiliary valve 68 is unseated. A small coil spring 14 is located between the cap and the end of the plug 66 and tends to hold the auxiliary valve 68 on its seat 66a except when the fluid fuel pressure in the bore 52 to the left of the valve piston 48 is enough to overcome the spring 14.

At 16 is shown a pump body and at 18 a pump plunger in a cylinder 19 the plunger being urged downwardly by a spring 80 working against a shoulder 82 of a sleeve 84 which slides on the pump body 16 and operatively engages the plunger H3 through a head 86 on the plunger secured to the sleeve 84. The plunger 18 has oil grooves 81 and is operated upwardly by an adjustable tappet head 88 which in turn is operatively raised by cam means not shown rotating in timed relation with the engine cycle. The cam means, which does not form part of this invention and may be of a type well known in the art, may be adjusted to vary the length and timing of the stroke of the plunger 18 for accelerating the engine. The sleeve 84 has an oil escape passage 90 to drain excess oil leaking down past the plunger 18. The pump body 16 is screwed into an aperture 9| in a projection 93 on the side of the valve body 18 and a tight joint is made by means of a gasket 92. A fuel pipe not shown is screwed into a tapped hole 94 and a port Q leads into the pump cylinder 19. The pump cylinder communicates with the bore 52 in the valve body l8.

On the top side of the valve body l8 are two plugs 98 and Hill which are screw threaded, one of which, 98, is in a threaded aperture 99a which leads through a passage 89 into the portion of the bore 52 on the right hand or fuel receiving side of the piston 48, while the other, 100, is in a threaded aperture lilia which leads through a passage WI into the portion of the bore 52 which contains the spring 58. In the plugs 88 and H are inserts I62 and I04, re-

spectively, having holes or ports I05 and I88 therein, forming cells H0 and H2 above and connected through constricted passages to the bore 52 on opposite sides of the valve piston 18.

The operation of the mechanism described 1 herein when the engine is runnin is as follows: The fuel injection system, except the cell l 12 in the plug 100, is full of fuel on both sides of the piston 48. The cell Ill] in the plug 98 is full of fuel oil at this time. While the tappet 8B is moving the pump plunger 18 upward, the fuel oil above the plunger 18 flows back into the oil line through the port 96 until the upper end of the plunger 78 covers the port 98. Thereafter, as

the plunger it continues to move upward, the

pressure of the .fuel oil rises rapidly in the bore 52 .on the fuel valve (right hand) side of the piston 48 a predetermined fluid pressure exerted by the plunger 18 through the fuel against the shoulder Ell of the piston 48 and, determined :by the strength of the spring 58, is reached, whereupon the differential fuel valve 46 opens to the left and allows fuel to pass the valve 46 and flow at high velocity out of the conical portion of the spray cone 46. As the fuel spray leaves the spray cone 40, it strikes air in the annular space 38 in the jet 3i! and carries the air with it. This air having flowed from the annular space 28 through the passages is heated. The fuel and air, therefore, mix to some extent while passing through the jet 32. On emengin from the jet 32, the mixture of fuel and air is projected at high velocity into the space in the base of the spray nozzle 34] and is further mixed with hot air drawn through the passage .26 from the top of the combustion chamber 16. The preheated fuel mixture is then projected through the spray nozzle 36 into the combustion chamber 1-6. It will be seen, therefore,

that hot air taken from the top of the combustion chamber is mingled first with the fuel as it emerges from the spray cone 4!] and again with more air as the fuel emerges from the jet 32. Since the air is hot and the fuel traveling at high velocity, it is broken up into tiny droplets cr particles which expand and vaporize by reason of the heat so that an excellent rapidly combustible mixture of fuel and air is produced. As already stated, the fuel pressure in the bore 52 rises rapidly after the pump plunger 18 has covered the port 96 and this pressure causes the piston 48 to move to the left in the bore 52 when the pressure exceeds the strength of the spring 58. Although the piston 48 may move only a very short distance to the left, the pressure of the air in the air cell H2 in the plug I00 rises somewhat and it acts as a cushion. Also there is some blow-by of fuel oil past the oil sealing grooves 50 of the piston 48 and this causes a further rise of pressure in the air cushion cell H 2 in the plug I110. The rising fuel oil pressure on the left side of the piston 48 approaches the fuel oil pressure on the valve side of the piston 48. This causes the fuel valve-45 to close rapidly when the plunger 18 stops its upward movement and produces a sharp cut-off of fuel flow through the spray cone 4B. The downward movement of the pump plunger 18 causes a partial vacuum in the bore 52 on the fuel valve side and this partial vacuum serves three purposes; first, to cause the fuel valve 45 to be more strongly forced against its seat 40 than otherwise and this takes place when the pressure in the combustion space of the engine is at the maximum, and, therefore, there will be no back flow of gases past the fuel valve 46; second, to cause the auxiliary valve 68 to be opened and allow excess fuel on the left-hand side of the piston 43 to flow back into the bore 52 on the righthand side of the valve'piston 48; and, third, it causes the pump cylinder 18 to be refilled with fuel oil for the next cycle of operation of the fuel pump when the plunger 18 clears the port 98 on its downward stroke.

Since the entire space on the left hand side of the valve piston ll is sealed off from the atmosphere and filled with fuel oil except for the air cell H2, the function of the auxiliary valve is to return excess fuel to the right side of the piston 48 which may have leaked past it during the pressure stroke of the pump plunger 18 and thus to restore normal fuel pressure on the left side of the piston 18 which is controlled by the pressure of the spring 14. This avoids the necessity of extremely close tolerance in the fit of the piston 48 in its bore 52 and reduces the cost of the mechanism.

The function of the plug 98 is to provide a. means of priming the fuel system with fuel oil the cell .HD is filled with oil before the plug s8 is inserted, The cell provides additional space n which partial vacuum may be created for 1111' ing the pump cylinder 19 on the downward stroke ofth-e plunger 18.

I claim;

I 1. A fuel injection devicefor internal combustion engines comprising, in combination with .a fuel pump having a plunger, a valve body havng a cylindrical bore therein, a valve seat having a fuel passage at one end of said bore, a valve member slidable in said bore, said valve member being formed. at one end as a piston of larger diameter fitting said :bore and at its other end as a valve element of comparatively smaller diameter seating toward said seat, said pump being connected to said bore between said piston and said valve seat, a valve spring urging said valve member toward and onto said seat, a cap enclosing said bore at its end opposite the seat, a closed air space forming an air cushion connecting with said opposite end of the bore and located above it and said opposite end of the bore being normally filled with fuel oil during operation, an axial passage in said piston interconnecting the spaces in the bore on o posite sides of the piston and a pressure relief valve disposed in said axial passage, said relief valve being adapted to open in response to a predetermined greater differential fluid pressure in said end of the bore opposite the seat with respect to the fluid pressure in the end of the bore toward the seat, said valve member being unseated to allow fuel injection upon the pressure stroke of said pump plunger and against said spring and air cushion and thereafter excess fuel in said opposite end of the bore flowing back 6 through said relief valve when its said differential pressure exceeds a predetermined amount upon the return stroke of the pump plunger.

2. The device as set forth in claim 1 in which the fuel pump is secured to the valve body as a unitary structure.

WILLIAM V. FALCON.

References Cited in the file of this patent UNITED STATES PATENTS 

